Evanescent luminescence excitation is of great interest in the analytical field, as the excitation is limited to the direct environment of the wave-guiding layer. In particular, Evanescent field excited fluorescence is a very important technology for biosensors because of its unique sensitivity.
A waveguide biosensor consists generally in the simplest case of a 3-layer system, a first substrate, an inorganic wave-conducting layer, and a second substrate comprising the sample for assaying. An example of a waveguide biosensor having an inorganic wave-conducting layer is disclosed in WO 95/33197. Waveguide biosensor with an inorganic wave-conducting layer on an inorganic substrate suffers in that the waveguide biosensor has an insufficient flexibility and high manufacturing cost. Further, bending and/or warming of a waveguide biosensor with an inorganic wave-conducting layer on an organic substrate, which is more time and thus cost effective to produce, often leads to a delamination of the polymeric substrate attached to the inorganic wave-conducting layer. Thus, there is the need to provide a waveguide biosensor having a high flexibility, high delamination resistance as well as a low vertical range of manufacture.
Methods and apparatus for detecting the evanescently excited luminescence of antibodies or antigens labelled with luminescent dyes are known and described, inter alia, in US-A1-2002/0110839. The arrangement claimed therein uses a system of a reaction matrix comprising a waveguide capable of guiding and channeling light and having on the surface of said waveguide a cladding layer having at least one area of depletion in form of nanowells wherein a substance placed within said depletion area can be illuminated by the evanescent wave of light channeled in said waveguide. The manufacture of a nanowells micro array-cladding layer requires a more complex and more accurate process. The quite small nanowells requires a more accurate and still more complex positioning of the bound molecules in all the wells, which leads to a further drawback.
Therefore, it is one object of the present invention to provide an optical waveguide sensor for use as a chemical or biosensor of detecting biological molecules, which can be easily produced, does not need a high precision, has a high flexibility, high delamination resistance and a low vertical range of manufacture so that said sensors can be used as disposable articles in view of low manufacture and material cost and has at the same time a sufficient high demand of the optical and detection quality of said sensor.